Field of the Invention
This invention relates to the use of catalytic amounts of Fe.sup.+2 and Fe.sup.+3 contributing compounds for preparing .alpha.-and .beta.-hydroxy oximes.
Description of the Prior Art
.alpha.- AND .beta.-HYDROXY OXIMES ARE WELL-KNOWN IN THE ART AND ARE GENERALLY USED FOR EXTRACTING METALS SUCH AS COPPER, COBALT AND NICKEL FROM AQUEOUS METAL ORE SOLUTIONS. Several methods for preparing these oximes are known in the art. For example, U.S. Pat. No. 3,449,066 describes a process for preparing aliphatic .alpha.-hydroxy oximes wherein the corresponding acyloin is reacted with a hydroxylamine salt under reflux conditions in an alcohol medium such as methanol. The reaction must be neutralized with a salt of a weak base such as anhydrous sodium acetate.
The .beta.-hydroxy oximes are generally aromatic in structure and are usually prepared by reacting the corresponding phenone with a hydroxylamine salt under reflux conditions in an alcohol medium and in the presence of a weak base such as anhydrous sodium acetate. Exemplary processes of this type are disclosed in U.S. Pat. No. 3,592,775.
Another process known in the art is the reaction of the corresponding acyloin for .alpha.-hydroxy oximes or the corresponding phenone for .beta.-hydroxy oximes with a Raschig hydroxylamine in an alcohol medium under reflux conditions. An advantage of this method over the aforementioned methods is that the pH is adjusted by use of NH.sub.3 instead of with the salt of a weak base, causing the effluent to be higher in ammonia but free of other materials.
Although any of the forementioned methods will produce an .alpha.-or .beta.-hydroxy oxime compounds suitable for extracting metals from an ore solution, all suffer from the disadvantage of requiring relatively long time for their preparation. Frequently 18-22 hours are required, especially when the product oxime includes aromatic groups.